使用两个柱合并，同时进行熔化

Question

dfa <- data.frame(numid = c(1,2), numt = c(3,5), date = c("2012-03-21 12:32:11", "2011-11-03 04:32:11"), session = c("sessionA", "sessionB"))
dfb <- data.frame(numid = c(1,1,2), nums = c(402,321,34), date = c("2012-03-21 12:52:11","2012-03-21 12:41:32","2011-11-04 04:32:11"), session = c("sessionA", "sessionA", "sessionB"))

我想使用列numid和session合并两个数据帧。然而，我希望精细数据帧的格式为dfb的熔化选项，其中numid与dfa相同，并且在会话列中也具有相同的值，添加dfa的日期。示例输出：

dff <- data.frame(numid = c(1,1,2), date_dfa = c("2012-03-21 12:32:11", "2012-03-21 12:32:11", "2011-11-03 04:32:11"), nums = c(402,321,34), date = c("2012-03-21 12:52:11","2012-03-21 12:41:32","2011-11-04 04:32:11"), session = c("sessionA", "sessionA", "sessionB"))

Answer 1

您可以尝试：

#Merge
Merged <- merge(dfa,dfb,by=c('numid','session'),suffixes = c('dfa','dfb'))
numid  session numt             datedfa nums             datedfb
1     1 sessionA    3 2012-03-21 12:32:11  402 2012-03-21 12:52:11
2     1 sessionA    3 2012-03-21 12:32:11  321 2012-03-21 12:41:32
3     2 sessionB    5 2011-11-03 04:32:11   34 2011-11-04 04:32:11